Systems and methods for controlling motion of detectors having moving detector heads

ABSTRACT

Systems and methods for controlling motion of detectors having moving detector heads are provided. One system includes a gantry and a plurality of detector units mounted to the gantry, wherein the plurality of detector units are individually movable including translational movement and rotational movement. The system further includes a controller configured to control movement of the plurality of detector units to acquire Single Photon Emission Computed Tomography (SPECT) data, wherein the movement includes both the translational movement and the rotational movement coordinated to position the plurality of detector units adjacent to a subject.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates generally to apparatus andmethods for diagnostic medical imaging, such as Nuclear Medicine (NM)imaging.

In NM imaging, systems with multiple detectors or detector heads may beused to image a subject, such as to scan a region of interest. Forexample, the detectors may be positioned adjacent the subject to acquireNM data, which is used to generate a three-dimensional (3D) image of thesubject.

Single Photon Emission Computed Tomography (SPECT) systems may havemoving detector heads, such as gamma detectors positioned to focus on aregion of interest. For example, a number of gamma cameras may be moved(e.g., rotated) to different angular positions for acquiring image data.The acquired image data is then used to generate the 3D images.

Resolution of gamma detectors is a convolution of the detectorresolution (mainly pixel size) and the collimator resolution. Collimatorresolution degrades with the distance of the collimator from thepatient. In conventional SPECT camera systems with multiple swingingdetector heads, the detectors swing about a fixed pivot (usually insidea protective case). As a result of the configuration of these systems,including the detectors and collimators, the gamma cameras often have tobe placed at an additional distance from the patient. This increase indistance results in a degrading of resolution.

Thus, known systems have degradation in imaging resolution as a resultof the limits to which the gamma cameras can move in proximity to thepatient because of the configuration of the detector head or collimatorused, and/or the types of control of movement of the gamma cameras.

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment, an imaging system is provided that includes a gantryand a plurality of detector units mounted to the gantry, wherein theplurality of detector units are individually movable includingtranslational movement and rotational movement. The imaging systemfurther includes a controller configured to control movement of theplurality of detector units to acquire Single Photon Emission ComputedTomography (SPECT) data, wherein the movement includes both thetranslational movement and the rotational movement coordinated toposition the plurality of detector units adjacent to a subject.

In another embodiment, an imaging system is provided that includes aplurality of pivoting detector units and at least one collimator coupledto at least one of the pivoting detector units. The collimator includescollimator bores of different lengths to form a non-planar face.

In another embodiment, a method for collimating a Nuclear Medicine (NM)detector is provided. The method includes providing a collimator havinga plurality of collimator bores extending through a body portion, whereat least some of the collimator bores have different lengths to form acurved face along one side of the body portion. The method also includesconfiguring the collimator for coupling to at least one detector module.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a Nuclear Medicine (NM) imagingsystem in accordance with an embodiment.

FIG. 2 is a diagram illustrating detectors having movement about oneaxis.

FIG. 3 is a diagram illustrating uncovered detectors in accordance withvarious embodiments.

FIG. 4 is a diagram illustrating detector movement in accordance withvarious embodiments.

FIG. 5 is a diagram illustrating a collimator in accordance with anembodiment having a higher resolution area.

FIG. 6 is a diagram illustrating a collimator arrangement in accordancewith an embodiment.

FIG. 7 is a diagram illustrating the manufacture of a collimator inaccordance with an embodiment.

FIG. 8 is a diagram illustrating interlocking sheets for the manufactureof a collimator in accordance with an embodiment.

FIG. 9 is a diagram illustrating a collimator arrangement in accordancewith another embodiment.

FIGS. 10 and 11 are diagrams illustrating a collimator arrangement inaccordance with another embodiment.

FIG. 12 is a diagram illustrating a collimator arrangement in accordancewith another embodiment.

FIG. 13 is a diagram illustrating a collimator arrangement in accordancewith another embodiment.

FIG. 14 is a diagram illustrating a collimator arrangement in accordancewith another embodiment.

FIG. 15 is a diagram illustrating an imaging system in accordance withan embodiment in which one or more configurations of detectors may beimplemented.

FIG. 16 is a diagram illustrates an imaging system in accordance withanother embodiment in which one or more configurations of detectors maybe implemented.

FIGS. 17 and 18 are diagrams illustrating motion of detectors inaccordance with an embodiment.

FIG. 19 is a diagram illustrating a detector arm configuration inaccordance with an embodiment.

FIG. 20 is a perspective view of an imaging system in accordance withanother embodiment.

FIG. 21 is a perspective view of an imaging system in accordance withanother embodiment.

FIG. 22 is a flowchart of a method in accordance with variousembodiments.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description of certain embodiments will be betterunderstood when read in conjunction with the appended drawings. To theextent that the figures illustrate diagrams of the functional blocks ofvarious embodiments, the functional blocks are not necessarilyindicative of the division between hardware circuitry. For example, oneor more of the functional blocks (e.g., processors or memories) may beimplemented in a single piece of hardware (e.g., a general purposesignal processor or a block of random access memory, hard disk, or thelike) or multiple pieces of hardware. Similarly, the programs may bestand alone programs, may be incorporated as subroutines in an operatingsystem, may be functions in an installed software package, and the like.It should be understood that the various embodiments are not limited tothe arrangements and instrumentality shown in the drawings.

As used herein, an element or step recited in the singular and proceededwith the word “a” or “an” should be understood as not excluding pluralof said elements or steps, unless such exclusion is explicitly stated.Furthermore, references to “one embodiment” of are not intended to beinterpreted as excluding the existence of additional embodiments thatalso incorporate the recited features. Moreover, unless explicitlystated to the contrary, embodiments “comprising” or “having” an elementor a plurality of elements having a particular property may includeadditional elements not having that property.

Various embodiments provide systems and methods for controlling themovement of a plurality of imaging detectors to position the imagingdetectors to acquire image data. For example, in various embodiments, animaging system having one or more Nuclear Medicine (NM) cameras havingan array of heads that are individually and independently movable isprovided. In some embodiments, one or more of the heads are capable of aplurality of types of movement, such as translation, rotation, pivoting,and/or swiveling. The NM cameras in various embodiments are configuredto acquire Single Photon Emission Computed Tomography (SPECT) data, suchas when moving the detector heads. For example, various embodimentsprovide combination movements or complex motion of the detectors, suchas a combination of up/down movement with swinging motion. In someembodiments, the motion may include, for example, side-to-side motion.

Additionally, imaging detectors or camera heads are coupled withcollimators in various embodiments. In some embodiments, collimators areprovided that have uneven bores, in particular, bores having differentlengths. For example, instead of having collimators that are “box like”shaped with all bores having the same length, different length bores(e.g., uneven lengths) may be provided. In some embodiments, the varyingcollimator bore length increases resolution at the central or middlesection of the detector and reduced or eliminates a gap between adjacentdetectors.

FIG. 1 is a schematic illustration of a NM imaging system 100 having aplurality of imaging detectors mounted on a gantry (which may bemounted, for example, in rows, in an iris shape, or otherconfigurations). In particular, a plurality of imaging detectors 102 aremounted to a gantry 104. In the illustrated embodiment, the imagingdetectors 102 are configured as two separate detector arrays 106 and 108coupled to the gantry 104 above and below a subject 110 (e.g., apatient), as viewed in FIG. 1. The detector arrays 106 and 108 may becoupled directly to the gantry 104, or may be coupled via supportmembers 112 to the gantry 104 to allow movement of the entire arrays 106and/or 108 relative to the gantry 104 (e.g., translating movement in theleft or right direction as viewed in FIG. 1). Additionally, each of theimaging detectors 102 includes a detector unit 114, at least some ofwhich are mounted to a movable detector carrier 116 (e.g., a support armor actuator that may be driven by a motor to cause movement thereof)that extends from the gantry 104. In some embodiments, the detectorcarriers 116 allow movement of the detector units 114 towards and awayfrom the subject 110, such as linearly. Thus, in the illustratedembodiment the detector arrays 106 and 108 are mounted in parallel aboveand below the subject 110 and allow linear movement of the detectorunits 114 in one direction (indicated by the arrow L), illustrated asperpendicular to the support member 112 (that are coupled generallyhorizontally on the gantry 104). However, other configurations andorientations are possible as described herein. It should be noted thatthe movable detector carrier 116 may be any type of support that allowsmovement of the detector units 114 relative to the support member 112and/or gantry 104, which in various embodiments allows the detectorunits 114 to move linearly towards and away from the support member 112.

Each of the imaging detectors 102 in various embodiments are smallerthan a conventional whole body or general purpose imaging detector. Aconventional imaging detector may be large enough to image most or allof a width of a patient's body at one time and may have a diameter or alarger dimension of approximately 50 cm or more. In contrast, each ofthe imaging detectors 102 may include one or more detector units 114coupled to a respective detector carrier 116 and having dimensions of 4cm to 20 cm and may be formed of Cadmium Zinc Telluride (CZT) tiles ormodules. For example, each of the detector units 114 may be 8×8 cm insize and be composed of a plurality of CZT pixelated modules (notshown). For example, each module may be 4×4 cm in size and have16×16=256 pixels. In some embodiments, each detector unit 114 includes aplurality of modules, such as an array of 1×7 modules. However,different configurations and array sizes are contemplated including, forexample, detector units 114 having multiple rows of modules.

It should be understood that the imaging detectors 102 may be differentsizes and/or shapes with respect to each other, such as square,rectangular, circular or other shape. An actual field of view (FOV) ofeach of the imaging detectors 102 may be directly proportional to thesize and shape of the respective imaging detector.

The gantry 110 may be formed with an aperture 118 (e.g., opening orbore) therethrough as illustrated. A patient table 120, such as apatient bed, is configured with a support mechanism (not shown) tosupport and carry the subject 110 in one or more of a plurality ofviewing positions within the aperture 118 and relative to the imagingdetectors 102. Alternatively, the gantry 104 may comprise a plurality ofgantry segments (not shown), each of which may independently move asupport member 112 or one or more of the imaging detectors 102.

The gantry 104 may also be configured in other shapes, such as a “C”,“H” and “L”, for example, and may be rotatable about the subject 110.For example, the gantry 104 may be formed as a closed ring or circle, oras an open arc or arch which allows the subject 110 to be easilyaccessed while imaging and facilitates loading and unloading of thesubject 110, as well as reducing claustrophobia in some subjects 110.

Additional imaging detectors (not shown) may be positioned to form rowsof detector arrays or an arc or ring around the subject 110. Bypositioning multiple imaging detectors 102 at multiple positions withrespect to the subject 110, such as along an imaging axis (e.g., head totoe direction of the subject 110) image data specific for a larger FOVmay be acquired more quickly.

Each of the imaging detectors 102 has a radiation detection face, whichis directed towards the subject 110 or a region of interest within thesubject. The radiation detection faces are each covered by or havecoupled thereto a collimator 122. The actual FOV for each of the imagingdetectors 102 may be increased, decreased, or relatively unchanged bythe type of collimator 122. As described in more detail herein, in someembodiments, the collimator 122 includes at least some collimator boreshaving different axial lengths.

In one embodiment, the collimator 122 is a multi-bore collimator, suchas a parallel hole collimator. However, other types of collimators, suchas converging or diverging collimators may optionally or alternativelybe used. Other examples for the collimator 122 include pinhole,parallel-beam converging, diverging fan-beam, converging or divergingcone-beam, multi-bore converging, multi-bore converging fan-beam,multi-bore converging cone-beam, multi-bore diverging, or other types ofcollimator.

Optionally, multi-bore collimators may be constructed to be registeredwith pixels of the detector units 114, which in one embodiment are CZTdetectors. However, other materials may be used. Registered collimationmay improve spatial resolution by forcing photons going through one boreto be collected primarily by one pixel. Additionally, registeredcollimation may improve sensitivity and energy response of pixelateddetectors as detector area near the edges of a pixel or inbetween twoadjacent pixels may have reduced sensitivity or decreased energyresolution or other performance degradation. Having collimator septadirectly above the edges of pixels reduces the chance of a photonimpinging at these degraded-performance locations, without decreasingthe overall probability of a photon passing through the collimator.

A controller unit 130 may control the movement and positioning of thepatient table 110, imaging detectors 102 (which may be configured as oneor more arms), gantry 104 and/or the collimators 122 (that move with theimaging detectors 102 in various embodiments, being coupled thereto). Arange of motion before or during an acquisition, or between differentimage acquisitions, is set to maintain the actual FOV of each of theimaging detectors 102 directed, for example, towards or “aimed at” aparticular area or region of the subject 110 or along the entire subject110. The motion may be a combined or complex motion in multipledirections simultaneously, concurrently, or sequentially as described inmore detail herein.

The controller unit 130 may have a gantry motor controller 132, tablecontroller 134, detector controller 136, pivot controller 138, andcollimator controller 140. The controllers 130, 132, 134, 136, 138, 140may be automatically commanded by a processing unit 150, manuallycontrolled by an operator, or a combination thereof. The gantry motorcontroller 132 may move the imaging detectors 102 with respect to thesubject 110, for example, individually, in segments or subsets, orsimultaneously in a fixed relationship to one another. For example, insome embodiments, the gantry controller 132 may cause the imagingdetectors 102 and/or support members 112 to move relative to or rotateabout the subject 110, which may include motion of less than or up to180 degrees (or more).

The table controller 134 may move the patient table 120 to position thesubject 110 relative to the imaging detectors 102. The patient table 120may be moved in up-down directions, in-out directions, and right-leftdirections, for example. The detector controller 136 may controlmovement of each of the imaging detectors 102 to move together as agroup or individually as described in more detail herein. The detectorcontroller 136 also may control movement of the imaging detectors 102 insome embodiments to move closer to and farther from a surface of thesubject 110, such as by controlling translating movement of the detectorcarriers 116 linearly towards or away from the subject 110 (e.g.,sliding or telescoping movement). Optionally, the detector controller136 may control movement of the detector carriers 116 to allow movementof the detector array 106 or 108. For example, the detector controller136 may control lateral movement of the detector carriers 116illustrated by the L arrow (and shown as left and right as viewed inFIG. 1). In various embodiments, the detector controller 136 may controlthe detector carriers 116 or the support members 112 to move indifferent lateral directions.

The pivot controller 138 may control pivoting or rotating movement ofthe detector units 114 at ends of the detector carriers 116 and/orpivoting or rotating movement of the detector carrier 116. For example,one or more of the detector units 114 or detector carriers 116 may berotated about at least one axis to view the subject 110 from a pluralityof angular orientations to acquire, for example, 3D image data in a 3DSPECT or 3D imaging mode of operation. The collimator controller 140 mayadjust a position of an adjustable collimator, such as a collimator withadjustable strips (or vanes) or adjustable pinhole(s).

It should be noted that motion of one or more imaging detectors 102 maybe in directions other than strictly axially or radially, and motions inseveral motion directions may be used in various embodiment. Therefore,the term “motion controller” may be used to indicate a collective namefor all motion controllers. It should be noted that the variouscontrollers may be combined, for example, the detector controller 136and pivot controller 138 may be combined to provide the differentmovements described herein.

Prior to acquiring an image of the subject 110 or a portion of thesubject 110, the imaging detectors 110, gantry 104, patient table 120and/or collimators 122 may be adjusted as discussed in more detailherein, such as to first or initial imaging positions, as well assubsequent imaging positions. The imaging detectors 102 may each bepositioned to image a portion of the subject 110. Alternatively, one ormore of the imaging detectors 102 may not be used to acquire data, suchas the imaging detectors 102 at ends of the detector arrays 106 and 108,which as illustrated in FIG. 1 are in a retracted position away from thesubject 110. Positioning may be accomplished manually by the operatorand/or automatically, which may include using, for example, imageinformation such as other images acquired before the currentacquisition, such as by another imaging modality such as X-ray ComputedTomography (CT), MRI, X-Ray, PET or ultrasound. In some embodiments, theadditional information for positioning, such as the other images, may beacquired by the same system, such as in a hybrid system (e.g., aSPECT/CT system). Additionally, the detector units 114 may be configuredto acquire non-NM data, such as x-ray CT data. In some embodiments, amulti-modality imaging system may be provided, for example, to allowperforming NM or SPECT imaging, as well as x-ray CT imaging, which mayinclude a dual-modality or gantry design as described in more detailherein.

After the imaging detectors 102, gantry 104, patient table 120, and/orcollimators 122 are positioned, one or more images, such asthree-dimensional (3D) SPECT images are acquired using one or more ofthe imaging detectors 102, which may include using a combined motionthat reduces or minimizes spacing between detector units 114. The imagedata acquired by each imaging detector 102 may be combined andreconstructed into a composite image or 3D images in variousembodiments.

In one embodiment, at least one of detector arrays 106 and/or 108,gantry 104, patient table 120, and/or collimators 122 are moved afterbeing initially positioned, which includes individual movement of one ormore of the detector units 114 (e.g., combined lateral and pivotingmovement). For example, at least one of detector arrays 106 and/or 108may be moved laterally while pivoted. Thus, in various embodiments, aplurality of small sized detectors, such as the detector units 114 maybe used for 3D imaging, such as when moving or sweeping the detectorunits 114 in combination with other movements.

In various embodiments, a data acquisition system (DAS) 160 receiveselectrical signal data produced by the imaging detectors 102 andconverts this data into digital signals for subsequent processing.However, in various embodiments, digital signals are generated by theimaging detectors 102. An image reconstruction device 162 (which may bea processing device or computer) and a data storage device 164 may beprovided in addition to the processing unit 150. It should be noted thatone or more functions related to one or more of data acquisition, motioncontrol, data processing and image reconstruction may be accomplishedthrough hardware, software and/or by shared processing resources, whichmay be located within or near the imaging system 100, or may be locatedremotely. Additionally, a user input device 166 may be provided toreceive user inputs (e.g., control commands), as well as a display 168for displaying images.

FIG. 2 schematically demonstrates a detector 151 within a housing 153having only a single rotating or pivoting point. In this configuration,when the detector 151 (e.g., a CZT detector) is equipped with a flatcollimator 157 (e.g., collimator having a planar face) is to rotateabout a fixed pivot point 155, in order to avoid collision with asubject 110 (illustrated as a substantially flat patient), anunavoidable gap 161 is created between the face of the collimator 157and the subject 110.

In operation, and as shown, for example, in FIG. 3, a combined motion ofthe detector units 114 is used to position the detector units 114 ormove the detector units 114 before, during, and/or after imaging. FIG. 3schematically depicts a plurality of detector units 114, all within onepatient-protecting cover 115. The coordinated rotational (or pivoting)and up/down motion seen in FIG. 3 are performed by each of the detectorunits 114 to reduce or minimize the distance from the face of thecollimator 117 and the subject 110. The optional cover 115 may beremoved, for example, when the detector units 114 are placed below thepatient table 120

More particularly, as shown in FIG. 3, one or more of the detector units114 may be positioned or repositioned using a combination of movementsthat are performed is some embodiments concurrently. It should be notedthat the movements of different detector units 114 likewise may beperformed simultaneously, concurrently, or sequentially. As illustratedin FIG. 3, one type of combined movement includes rotational movement(illustrated by the R arrow, which may be or include pivoting movementin some embodiments) and linear or translation movement (illustrated bythe T arrow). It should be noted that while the translation movement isillustrated as up and down in FIG. 2, translation movement in othertransverse or perpendicular directions may be provided, such as left andright.

Additionally, the rotating movement may be provided about differentrotating axes or points, such as about a rod or at a pivot point. InFIG. 2, the rotation is about an axis 170, which may be a rotation orpivot point. For example, depending on the orientation of the axis 170,the detector units 114 may rotate in different directions.

It should be noted that depending on the state of movement of thedetector units 114 and the position thereof, a distance D exists betweenthe detector units 114 and the front face 174 of the housing (not shown)of the detector units 114. For example, as illustrated in FIG. 4, aplurality of detector units 114 each having a respective housing 150 maybe provided. As can be seen, a range of motion (illustrated by the Marrow) within the housing may be provided (up and down as seen in FIG.4) in addition to rotational movement (and may be defined or set basedon the object to be scanned). The rightmost detector unit 114 in FIG. 4shows a movement pattern in accordance with one embodiment that allowsthe housings 150 to be positioned adjacent each other with reduced orminimal distance therebetween. As can be seen, by translating androtating the detector units 114, the angle of the detector units 114 maybe changed to focus the detector units 114 at different views, whilemaintaining a small footprint for the housing 150. In some embodiments,no housings 150 are provided.

It should be noted that the various movements of the detector units 114may be provided using any suitable drive and control means, such asusing one or more motors. Additionally or optionally, a proximity sensor152 or other patient safety device may be used to detect contact orimpending contact with a patient. The proximity sensor 152 may beprovided in some embodiments as known in the art.

In various embodiments, a collimator 160 arrangement may be providedhaving variable length bores, for example, as illustrated in FIG. 5. Inthis embodiment, collimator bores 166 in a middle section 162 of thecollimator 160 have a greater length (and different lengths) than thecollimator bores 166 in side sections 164 of the collimator 160.Accordingly, as a result of the longer bore lengths in the middlesection 162, a higher resolution imaging portion or area is defined whencompared to the shorter lengths of collimator bores 166 in the sidesections 164 (as distance from the object being scanned is related toresolution). In the illustrated embodiment, a top portion 168 and abottom portion 170 of the collimator are shown as separate merely forease of explanation and illustration and in various embodiments thecollimator bores 166 from top to bottom as seen in FIG. 5 are singlechannels or pieces.

As can be seen in the illustrated embodiment, the length of thecollimator bores 166 decreases from a middle of the middle section 162,through the middle section 162 and to ends of the end sections 164.Thus, in this embodiment, a smoothly curved or arcuate face 172 isformed. It should be noted that the curvature of the face 172 may bevaried by changing the amount that the lengths of the collimator bores166 (such as adjacent collimator bores 166) are different. It shouldalso be noted that some of the collimator bores 166 may have the samelength, such as adjacent collimator bores 166 or collimator bores 166 onopposite sides (from left to right) of the collimator 160. Additionally,it should be noted that the face in various embodiments is not limitedto be smoothly curved, but may take different configurations, such asother different non-planar configurations (e.g., concave, convex,polygonal, among others).

In some embodiments, the amount of curvature may be varied at onlycertain portions along the face 172 to change the slope of the curve ordifferent amount of curvature may be provided such as to provide anasymmetric face 172. Additionally, other variations and modificationsare contemplated. For example, the length of the collimator bores 166may be varied differently such as in a stepwise manner such that asmooth face 172 is not provided.

The collimator 170 may be provided as part of the imaging unit 114 todefine a variable sensitivity and resolution detector module 180 asshown in FIG. 6. Thus, with the collimator 170, variable sensitivity andresolution may be provided that allows for focused scanning with only aportion of the module 180, for example, performing focused scanningusing only image data acquired within the middle section 162. In oneembodiment, focused scanning with a partial module may be performed forhigh resolution brain imaging.

It should be noted that although the housing of the module 180 isillustrated as circular (e.g., circular cross-section) within thecircular cross-section region 181 in various embodiments, the housingmay have different shapes as desired or needed. Additionally, thelocation of the components in the module 180 may be varied and differentconfigurations or sizes also may be provided. In the illustratedembodiment, a detector material 184 (such as CZT) is positioned adjacentand behind the collimator 160 as viewed in FIG. 5. In one embodiment,the detector material 184 may have a pixelated structure that isregistered with the collimator bores 166 (e.g., one pixel per collimatorbore 166). Electronics 186 are coupled to the detector material 184,such as known in the art to read out signals to be processed.Additionally, shielding 188 is provided around the collimator 160,detector material 184, and electronics 186. A holder 190 or othersupport (e.g., bracket) is provided within the housing, which may take aconfiguration to maintain the position of the components therein orallow movement as described in more detail herein.

Modifications and variations are contemplated. For example, air coolingmay be provided through an aperture (not shown), such as in theshielding 188 on the top of the module 180 as viewed in FIG. 6. Itshould be noted that the resolution at the central portion of thecollimator 172 is further improved as the face of the collimator 172 ata central portion is closer to the subject 110 (as well as having longerbores). For example, the distance seen in FIG. 2 (showing a conventionaldetector arrangement) is avoided at least for some portion of the faceof the collimator and some pivot positions. This increase in resolutionmay contribute to better image quality.

The collimator 160 may be formed in any suitable manner. In oneembodiment, as illustrated in FIG. 7, a plurality of tubes 190 (e.g.,lead tubes) are glued together as illustrated at (a). Thereafter, thetubes 190 are filled, for example, with a molten wax at (b). The tubes190 are then cut at (c) to form a curved face 192 at (c) (e.g., a curvedface along one side of the body portion). For example, the tubes 190 maybe cut to size or shape with a wire saw or other cutting device. Thecutting may be performed to form tubes 190 have different lengths asdescribed in more detail herein. Thereafter the wax is removed at (d)such that the tubes 190 now form different length bores for a collimator194. Optionally the collimator is attached to a pixelated detector in aregistered fashion such that at least some septa between bores arepositioned over boundaries between pixels.

The manufacturing process may include using a plurality of interlockingsheets, such as the set of sheets 200 or 202 as shown in FIG. 8. Forexample, the sheets may be sized (e.g., length) and shaped to define avariable bore length collimator as described herein. The set of sheets200 or 202 may correspond to different sections or portions of thecollimator, such that complementary cuts 204 a and 204 b are formed toallow interlocking of the sheets 200 or 202 (top and bottom sheets asviewed in FIG. 7).

In some embodiments, two modules may be provided per detector head asshown in FIG. 9. However, it should be appreciated that additionalmodules may be provided (and the two modules shown are forillustration). In particular, within a single housing 210, two sets ofCZT material 184 and corresponding electronics 186 may be provided. Inthis embodiment, a collimator 212 is similarly provided with collimatorbores 214 having different lengths. As can be seen, in this embodiment,different sections 216 may be provided that having different curvatures,which may be determined based on the type and amount of movement to beprovided within the housing 210. Again, as should be appreciated, thesections 216 are merely shown for ease of description and are notnecessarily separate pieces joined together, but may be a single piece.Thus, in this embodiment, the collimator 212 has a curved face 218 thatextends across two modules 220 defined by the two sets of CZT material184 and corresponding electronics 186. It should be appreciated thatadditional modules 220 may be encompassed by the collimator 212 asdesired or needed.

It should be noted that each detector unit may comprise an array ofmodules, for example 2×2, 2×3, 2×4 modules, etc. Generally, the pixelsize of a pixelated NM detector may be selected to be about 1.5 mm to 3mm, which may be due to physical constrains. In some embodiments,wherein the collimator is a registered collimator, the width of thecollimator bore is the pixel to pixel separation minus the septa'sthickness. The optimal length of the longest and shortest collimatorbore may then be selected by knowing the desired minimum and maximumresolution and the tradeoff between the resolution and sensitivity atthe working distance from the organ of interest. To be able to pivotwithout collision with the cover (or the nearby detector) the entiremoving part of the detector, including the sensor, the collimator,electronics and optional shielding fit within a circular cross-sectionregion 181 (e.g., cylindrical shielding or cover) centered about thepicturing point (such as shown, for example, in FIGS. 6, 9, 10, and 11).When using a wider detector, for example made of two or three side byside modules, a larger aspect ration collimator (the ratio between thelengths of the longest and shortest collimator tubes) may be created,while efficiently filling the limiting circle.

It should be noted that different configurations of collimators may beprovided. For example, in some embodiments, a collimator with a doublepitch compared to the detector pitch may be provided (e.g., the pitch ofcollimator being twice the pitch of the detector). However, otherdifferent relative pitches may be provided. Using a collimator with adouble pitch compared to the detector pitch allows for reducing thelength of the collimator by half and reducing respectively the diameterof the detector unit. Thus, for example, the smaller detector unitallows the detector unit to be positioned closer to the subject beforecollision or colliding with adjacent detectors.

Different configuration of collimators also may be provided, such ascurved in two-dimensions or three-dimensions. For example, as shown inFIGS. 10 and 11, which are isometric illustrations of FIGS. 6 and 9, acollimator 234 (which may be embodied as the collimator 172) may beprovided that has varied bore length transverse to a longitudinal axis Lof the detector 230. In this embodiment, the collimator bores 236 fromfront to back as viewed in FIGS. 9 and 10 have the same bore length, butthe bore length is varied from side to side. An axis 238 of rotation maybe provided as illustrated in FIG. 10 such that the curved face 240rotates or swings about or parallel to the axis 238. However, in otherembodiments, the axis 238 may be changed such that the curved face 240may rotate transverse to the axis 238, such as if the axis 238 ispositioned from one side to an opposite side of the detector 230 insteadof from front to back as shown.

In some embodiments, a collimator 250 with a face 252 that curves from acenter 254 in two-dimensions as shown in FIG. 12. For example, thecurved face 252 is semi-spherical in this embodiment to allow swinging,for example, in two different directions (e.g., two orthogonaldirections as illustrated by the arrows). This embodiment may be used,for example, for a detector pivoting in two directions.

Other variations are contemplated. For example, as shown in FIGS. 13 and14, a collimator 260 may be provided with variable length bores 262.However, in these embodiments, unlike the embodiments shown in FIGS. 5and 8, respectively (where like numerals represent like parts), afan-beam type collimation arrangement is provided instead of aparallel-hole arrangement. As can be seen, the bores 262 in thisembodiment are angled towards a center region of the detector. Again, asshould be appreciated, the bores 262 have different lengths to form acurved face 264. It should be noted that the fan beam configurationfurther reduces the distance from the face of the collimator to thepatient at least for some portion of the face of the collimator and somepivot positions while efficiently remain within the circle 181 (e.g.,limiting circle). This increase in resolution may contribute to betterimage quality. Additionally, as can be seen in FIG. 14, for a widedetector, the length of the tubes one the edges of the detector issimilar to the length of the tubes in the center. Thus thisconfiguration may provide a more even resolution across the detector,while at the same time reducing the distance to the patient.

Thus, various embodiments provide different motions of detector units,as well as different arrangements of collimators to allow the detectorunits to be positioned closer together and closer to the object to bescanned than conventional systems.

It should be noted that various embodiments may be implemented indifferent system configurations. For example, as shown in FIG. 15, animaging system 270 may be provided that includes a gantry 272 with abore therethrough. The gantry 272 may have coupled thereto differentimaging detectors, for example, the imaging detectors 102 (as shown inFIG. 1). In this embodiment, the subject 110 is positioned on a patienttable 120 that includes a support 276 (e.g., a patient table or bedmechanism) that allows movement of the patient table 120 as describedherein. For example, the subject 110 may be moved upwards/downwards orleft/right (along the examination axis) as viewed in FIG. 15. Thus, thesubject 110 may be moved through the bore 274 and imaged as described inmore detail herein, using one or more of the detector and/or collimatorconfigurations described herein. Accordingly, in this embodiment, thesystem moves the subject 110 along the examination axis.

In another embodiment, for example, as shown in FIG. 16, and imagingsystem 280 may be provided wherein the imaging detectors 282 (which maybe embodied as the imaging detectors 102 shown in FIG. 1) are positionedaround at least a portion of the subject 110 (in some embodiments spacespartially or entirely around the subject 110). For simplicity and easeof description, only the detectors 282 and subject 110 are shown.However, one or more of the other system components as described hereinare provided. The detectors 282 may be controlled or operated in thisembodiment as described in more detail herein.

Thus, various embodiments may provide different configurations forpositioning the detectors and/or subject 110 with respect to each other.The movement of the detectors may be, for example, radially orrotatably. In one embodiment, as shown in the imaging system 190 ofFIGS. 17 and 18, a plurality of detectors 292 (e.g., the imagingdetectors 102 shown in FIG. 1), are positioned and spaced evenly, suchas distributed along a gantry evenly along the circumference of thegantry. For example, the detectors 292 are shown as spaced apart by 15degrees, but other spacings may be provided. However, an uneven spacingand/or additional or fewer detectors 102 may be provided. As can beseen, the detectors 292 are movable radially inward and outward toposition the detectors 292 adjacent to the subject 110 for imaging(shown in FIG. 18 in an imaging position or state). Thus, in thisembodiment, the detectors 292 are shown in an outermost position in FIG.17 and in an imaging position in FIG. 18. As should be appreciated, thedetectors 292 are movable different distances (e.g., one or moredetectors 292 moved different distances) depending on the size, shape,etc., of the subject 110.

The mechanism or components to moving the imaging detectors in variousembodiments may be provided using different arrangements. Onearrangement 300 is shown in FIG. 19 illustrating an imaging detectorconfiguration wherein a detector head 302 is mounted at one end of anarm 304 that includes a rail 306 to allow radial movement, such as shownin FIGS. 17 and 18. The movement may be controlled using a radial motionmotor 308. The detector head 302 in this embodiment includes a pluralityof imaging modules 310 (illustrated as CZT modules) that may be alignedin one or more rows (a single row is illustrated in the embodimentshown). As can be seen, a collimator 312 may be provided and coupled toone or more of the imaging modules 310. The collimator 312 may beprovided as described herein. Additionally, the imaging modules 310 arecoupled to a support 314 (e.g., a rod) that allows rotation or pivotingmovement of the imaging modules 310 within the detector head 302. Forexample, a motor, such as a sweep motor 314 may be provided to controland move the imaging modules 310 to sweep across a region of interest(e.g., rotate or pivot a defined number of degrees).

Additionally, different configurations may be provided. For example,within a single cover or a single detector head, multiple detector unitsor modules may be provided. Additionally, one or more detectors may befixed or mounted (or within) the patient table 120 or a support portionthereof.

It should be noted that a plurality of arms supporting the detectorunits may be provided in different configurations. For example, as shownin FIG. 20, a system 320 may be provided with a gantry 322 having aplurality of arms 324 (e.g., movable supports as described herein) thatextend and/or are movable radially inward and outward from the gantry292. It should be noted that the arms 324 are spaced apartcircumferentially around the entire bore 326 in this embodiment. It alsoshould be noted that additional or fewer arms and different spacingbetween arms 324 may be provided. The arms 324 may be movable asdescribed herein and may be embodied as the detector carriers 116 (shownin FIG. 1) in some embodiments. Additionally, each arm 294 may supportone or more detector units or modules (e.g., the detector units 114shown in FIG. 1). Other variations include arms 324 that are providedalong only a portion of the circumference of the bore 326 as illustratedin the system 330 of FIG. 21. It should be noted that although the arms324 are illustrated along about 180 degrees, the arms 294 may beprovided along more or less of the bore 326, such as more or less than180 degrees. It should be noted that for the configuration shown in FIG.21, rotations greater than 180 degrees may be used to provide imaging inboth prone and supine positions of the subject 110. For example, in someembodiments, rotation of about 210 degrees is provided. However, therotation may be more or less than 210 degrees as desired or needed.

Additionally, different configurations may be provided. For example, alinear type of design may be provided, such as described and shown inFIG. 11 in co-pending U.S. patent application Ser. No. 14/016,943,entitled “Methods and Apparatus for Imaging with Detectors having MovingDetector Heads”, which is hereby incorporated by reference in itsentirety.

Various embodiments also provide a method 340 as shown in FIG. 22. Themethod 270 includes providing a detector array at 342, for example, aCZT array with associated electronics as described herein. A collimatoris coupled to the detector array at 344. For example, a collimator withdifferent length bores and/or a curved face as described herein may beused. However, in other embodiments, a planar face collimator may beused. The method 340 additionally includes controlling movement inmultiple directions to move the detector array at 346. For example, asdescribed herein, the detector array may be translated and rotated orswung concurrently.

It should be noted that the various embodiments may be implemented inhardware, software or a combination thereof. The various embodimentsand/or components, for example, the modules, or components andcontrollers therein, also may be implemented as part of one or morecomputers or processors. The computer or processor may include acomputing device, an input device, a display unit and an interface, forexample, for accessing the Internet. The computer or processor mayinclude a microprocessor. The microprocessor may be connected to acommunication bus. The computer or processor may also include a memory.The memory may include Random Access Memory (RAM) and Read Only Memory(ROM). The computer or processor further may include a storage device,which may be a hard disk drive or a removable storage drive such as asolid-state drive, optical disk drive, and the like. The storage devicemay also be other similar means for loading computer programs or otherinstructions into the computer or processor.

As used herein, the term “computer” or “module” may include anyprocessor-based or microprocessor-based system including systems usingmicrocontrollers, reduced instruction set computers (RISC), ASICs, logiccircuits, and any other circuit or processor capable of executing thefunctions described herein. The above examples are exemplary only, andare thus not intended to limit in any way the definition and/or meaningof the term “computer”.

The computer or processor executes a set of instructions that are storedin one or more storage elements, in order to process input data. Thestorage elements may also store data or other information as desired orneeded. The storage element may be in the form of an information sourceor a physical memory element within a processing machine.

The set of instructions may include various commands that instruct thecomputer or processor as a processing machine to perform specificoperations such as the methods and processes of the various embodiments.The set of instructions may be in the form of a software program. Thesoftware may be in various forms such as system software or applicationsoftware and which may be embodied as a tangible and non-transitorycomputer readable medium. Further, the software may be in the form of acollection of separate programs or modules, a program module within alarger program or a portion of a program module. The software also mayinclude modular programming in the form of object-oriented programming.The processing of input data by the processing machine may be inresponse to operator commands, or in response to results of previousprocessing, or in response to a request made by another processingmachine.

As used herein, the terms “software” and “firmware” are interchangeable,and include any computer program stored in memory for execution by acomputer, including RAM memory, ROM memory, EPROM memory, EEPROM memory,and non-volatile RAM (NVRAM) memory. The above memory types areexemplary only, and are thus not limiting as to the types of memoryusable for storage of a computer program.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the variousembodiments without departing from their scope. While the dimensions andtypes of materials described herein are intended to define theparameters of the various embodiments, they are by no means limiting andare merely exemplary. Many other embodiments will be apparent to thoseof skill in the art upon reviewing the above description. The scope ofthe various embodiments should, therefore, be determined with referenceto the appended claims, along with the full scope of equivalents towhich such claims are entitled. In the appended claims, the terms“including” and “in which” are used as the plain-English equivalents ofthe respective terms “comprising” and “wherein.” Moreover, in thefollowing claims, the terms “first,” “second,” and “third,” etc. areused merely as labels, and are not intended to impose numericalrequirements on their objects. Further, the limitations of the followingclaims are not written in means-plus-function format and are notintended to be interpreted based on 35 U.S.C. § 112, sixth paragraph,unless and until such claim limitations expressly use the phrase “meansfor” followed by a statement of function void of further structure.

This written description uses examples to disclose the variousembodiments, including the best mode, and also to enable any personskilled in the art to practice the various embodiments, including makingand using any devices or systems and performing any incorporatedmethods. The patentable scope of the various embodiments is defined bythe claims, and may include other examples that occur to those skilledin the art. Such other examples are intended to be within the scope ofthe claims if the examples have structural elements that do not differfrom the literal language of the claims, or the examples includeequivalent structural elements with insubstantial differences from theliteral languages of the claims.

What is claimed is:
 1. An imaging system comprising: a gantry includingfirst and second support members; a plurality of detector units mountedto the gantry, the plurality of detector units individually movableincluding translational movement and rotational movement, wherein theplurality of detector units include a first group of detector units in afirst array mounted to a first support member and a second group ofdetector units in a second array mounted to a second support member,wherein the first array and second array are disposed on opposite sidesof a subject to be imaged, wherein the first detector units areconfigured to move parallel to each other and with the first supportmember along a translational direction parallel to the first and secondsupport members for the translational movement, and wherein the seconddetector units are configured to move parallel to each other and withthe second support member along the translation direction for thetranslational movement; and a controller configured to control movementof the plurality of detector units to acquire Single Photon EmissionComputed Tomography (SPECT) data, the movement including both thetranslational movement and the rotational movement coordinated toposition the plurality of detector units adjacent to the subject.
 2. Theimaging system of claim 1, wherein the controller is configured tocontrol one or more of the plurality of detector units to concurrentlyperform the translational movement and the rotational movement.
 3. Theimaging system of claim 1, further comprising a housing for each of theplurality of detector units, wherein the plurality of detector units aremovable within respective housings.
 4. The imaging system of claim 3,wherein the rotational movement comprises rotating motion relative tothe housing and within the housing.
 5. The imaging system of claim 1,further comprising at least one collimator coupled to a correspondingone of the plurality of detector units and disposed within a housing ofthe corresponding one of the plurality of detector units, the collimatorhaving collimator bores of different lengths to form a non-planar face,wherein the non-planar face has a shape corresponding to an interior ofthe housing of the corresponding one of the plurality of detector units.6. The imaging system of claim 5, wherein the different lengths ofcollimator bores define a higher resolution region in a middle sectionof the collimator.
 7. The imaging system of claim 5, further comprisinga plurality of cadmium zinc telluride (CZT) pixilated detector moduleswithin at least one of the plurality of detector units, the plurality ofmodules coupled to a single collimator.
 8. The imaging system of claim5, wherein the non-planar face extends along one axis.
 9. The imagingsystem of claim 5, wherein the non-planar face is non-planar inthree-dimensions to form a semi-spherical shape.
 10. The imaging systemof claim 5, wherein the collimator bores are aligned to form a parallelhole type collimation wherein the collimator bores are aligned inparallel.
 11. The imaging system of claim 5, wherein the collimatorbores are aligned to form a fan-beam type collimation.
 12. The imagingsystem of 1, further comprising an imaging unit forming part of theimaging system and configured to acquire image information differentthan the SPECT data, the controller configured to control movement ofthe plurality of detector units to focus at least one of the pluralityof detector units on a region of interest, wherein the movement iscontrollable by at least one of manual positioning, automatically usingimage information from different imaging modality separate from theimaging system, or automatically using image information from theimaging unit.
 13. The imaging system of 1, wherein the plurality ofdetector units are configured to acquire Single Photon Emission ComputedTomography (SPECT) data, and further comprising an x-ray ComputedTomography (CT) imaging unit forming part of a combined SPECT/CT imagingsystem and configured to acquired CT image information, the controllerconfigured to control movement of the plurality of detector units tofocus at least one of the plurality of detector units on a region ofinterest, wherein the movement is controllable automatically using theCT image information acquired by the CT imaging unit.
 14. The imagingsystem of 1, wherein the plurality of detector units are configured toacquire Single Photon Emission Computed Tomography (SPECT) data, andfurther comprising a stand-alone x-ray computed tomography (CT) imagingunit configured to acquired CT image information, the controllerconfigured to control movement of the plurality of detector units tofocus at least one of the plurality of detector units on a region ofinterest, wherein the movement is controllable automatically using theCT image information acquired by the stand-alone x-ray CT imaging unit.15. The imaging system of 1, further comprising a collimator is coupledto at least one of the plurality of detector units, the collimatorhaving twice the pitch compared to a pitch of the detector unit to whichthe collimator is coupled.